Bearing construction for a turbine blade

ABSTRACT

A bearing construction for rotationally supporting a wind turbine blade relative to a wind turbine hub, comprising a dynamic frame connecting the turbine blade and a static frame connecting the turbine hub. The dynamic frame is rotationally supported relative to the static frame by first and second axially spaced bearings. The dynamic and static frames comprise first and second bearing seats for the first and second bearings, respectively, and a first conical section having a cone base and a cone apex, and two or more frame legs circumferential openings in between. The dynamic and static frames are mutually overlapping, wherein the frame legs of one frame pass through openings between the frame legs of the other frame. The first conical sections of the static frame and the dynamic frame are oriented in the same direction, whereby a bearing seat is provided at the cone apex of each first conical section.

CROSS REFERENCE TO RELATED APPLICATION

This is a United States National Stage application claiming the benefitof International Application Number PCT/EP2014/056327 filed on 28 Mar.2014, which claims the benefit of International Application NumberPCT/EP2013/057048 filed on 3 Apr. 2013, both of which are incorporatedherein by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of pitch bearings forenabling a turbine blade to be rotated relative to a turbine hub.

BACKGROUND TO THE INVENTION

Typically, wind turbine blades are connected to the hub using a slewingbearing with a diameter that is approximately equal to the diameter ofthe blade root. Wind turbines are becoming larger and larger, and theblade root can have a diameter of more than 3 metres. A slewing bearingwith an equivalent diameter generates a substantial amount of friction.Also, the slewing bearings experience a high level of wear, due to therelatively small back and forth rotations that the bearing undergoesduring operation, especially when individual pitch control is applied,and due to the associated difficulty of maintaining a good lubricationfilm. Consequently, the use of slewing bearings and other types ofrolling element bearings as pitch bearings in wind turbines hasdisadvantages.

An alternative design for a pitch bearing assembly is disclosed inDE2855992. The assembly comprises two axially spaced bearings which areconnected to the blade and hub respectively via two mutually overlappingand oppositely oriented conical structures. The bearings are arranged atthe cone apices, the apex of each cone lying in a base plane of theother, and have a diameter that is considerably less than the blade rootdiameter. This is advantageous in terms of reducing friction.

The mutually overlapping conical structures of this pitch bearingassembly enable a limited amount of relative rotation between the huband the blade. The conical structures have three spokes, meaning that ifthe spokes were infinitely thin, a relative rotation of 120 degreeswould be possible. However, the spokes need to be sufficiently robust totransmit the high loads that act on the turbine blade. As the spokesbecome thicker, the angular range of the relative rotation decreases.

Consequently, there is room for improvement in terms of providing abearing construction comprising mutually overlapping conical structureswhich possess sufficient strength and enables an optimal range ofrelative angular rotation.

SUMMARY OF THE INVENTION

The present invention resides in a bearing construction for rotationallysupporting a wind turbine blade relative to a wind turbine hub,comprising a dynamic frame configured for connection to the turbineblade and a static frame configured for connection to the turbine hub.The dynamic frame is rotationally supported relative to the static frameby means of first and second axially spaced bearings, whereby each ofthe dynamic and static frame comprises a first bearing seat for thefirst bearing and a second bearing seat for the second bearing. Further,each of the dynamic and static frame comprises a first conical sectionhaving a cone base and a cone apex, and two or more frame legs withopenings in between. The dynamic and static frames are mutuallyoverlapping, such that the frame legs of one frame pass through theopenings between the frame legs of the other frame. According to theinvention, the first conical section of the static frame and of thedynamic frame are oriented in the same direction, whereby the cone apexof each first conical section is provided with a bearing seat.

As a result of orienting the conical sections in the same direction, apenetration region—where the frame legs of the static and dynamic framespass through each other—can be arranged at a large-diameter region ofthe static frame and of the dynamic frame. Consequently, the frame legsmay be executed with a thickness that provides the necessary strength,without overly restricting the degree of relative rotation between thestatic and dynamic frames. In a preferred example, each of the dynamicand static frames has three frame legs arranged at even intervals,whereby approximately 100 degrees of relative rotation is possible.

In a first embodiment of the invention, the static and dynamic framescomprise only a first conical section. The second bearing seat of thedynamic frame and of the static frame is then arranged in a centralportion of the cone base of the respective frame. In one example, thesecond bearing seat of the dynamic frame is arranged in the plane of thecone base of the dynamic frame. The dynamic frame legs then extend in apurely radial direction between the second bearing seat and the conebase of the dynamic frame. The static frame legs connect the cone baseof the static frame with the second bearing seat of the static frame andpreferably comprise an axial extension and a radial extension. The axialextension of the static frame legs extends from the cone base and passesthrough the openings between the dynamic frame legs, before extending aradial direction to the second bearing seat. The penetration region canthus be arranged at a large-diameter region of both frames.

In a further example, the second bearing seat of the static frame isarranged in the plane of the cone base of the static frame and haspurely radially extending static frame legs. The dynamic frame legs thensuitably comprise an axial extension and a radial extension as describedabove.

In a second embodiment of the invention, one or both of the static anddynamic frames comprises oppositely oriented first and second conicalsections, and have an essentially diamond shape. The advantage of adiamond-shaped frame is that the force lines through the frame legs arerelatively shorter, enabling less material to be used. This isbeneficial in terms of weight reduction.

In one example, both frames comprise first and second conical sectionswhich are connected by a common cone base. The first bearing seat of thestatic frame and of the dynamic frame is arranged at the cone apex ofthe corresponding first conical section, and the second bearing seat ofthe static frame and of the dynamic frame is arranged at the cone apexof the corresponding second conical section. Suitably, the frame legs ofat least one of the dynamic and static frames form part of a conicalsection of that frame.

The first bearing seat of the static frame and of the dynamic frame willbe designated as the bearing seat for a hub-side bearing of the bearingconstruction. Likewise, the second bearing seat of the static frame andof the dynamic frame will be designated as the bearing seat for ablade-side bearing of the bearing construction.

It should be noted that the hub-side bearing seat of the static framecan be a shaft element for receiving an inner ring of the hub-sidebearing or can be a housing element for receiving an outer ring of thehub-side bearing. Likewise, the blade-side bearing seat of the staticframe can be a shaft element for receiving an inner ring of the hub-sidebearing or can be a housing element for receiving an outer ring of theblade-side bearing. Similarly, the hub-side bearing seat of the dynamicframe can be a shaft element for receiving the inner ring of thehub-side bearing or can be a housing element for receiving the outerring of the hub-side bearing, and the blade-side bearing seat of thedynamic frame can be a shaft element for receiving the inner ring of theblade-side bearing or can be a housing element for receiving the outerring of the blade-side bearing.

When the hub-side and blade-side bearing seats of one the frames isformed by a shaft element, the seats may be provided on axially spacedportions of the same shaft section. Alternatively, the frame in questionmay comprise two short shaft sections. It is also possible for thehub-side bearing seat of a frame to be configured for connection to e.g.the outer ring of the hub-side bearing while the blade-side seat of thesame frame is configured for connection to the inner ring of theblade-side bearing.

Preferably, the blade-side bearing and the hub-side bearing comprises aradial spherical plain bearing. This type of bearing has advantageousproperties in terms of wear resistance, which is important in pitchbearing applications where the majority of rotational movements aresmall back-and-forth oscillations.

The static frame of the bearing construction is mounted to the hub. Insome examples, the static frame comprises a cylindrical hub interfacefor connection to the hub. The hub interface suitably comprises acylindrical connection portion that is joined to the cone base of thestatic frame by the static frame legs. The dynamic frame legs may formpart of a conical section that connects the cone base of the dynamicframe to the bearing seat of the hub-side bearing.

In other examples, the cone base of the static frame is mounted to thehub. The dynamic frame may then further comprise a cylindrical bladeinterface to which the turbine blade is connected. The blade interfacesuitably comprises a cylindrical connection portion that is joined tothe cone base of the dynamic frame by the dynamic frame legs. The staticframe legs may form part of a conical section that connects the conebase of the static frame to the bearing seat for the blade-side bearing.

When the cone base of the static frame is connected to the turbine hub,the bearing seat for the hub-side bearing may be arranged in a centralregion of the hub, close to an axis of the turbine main shaft. Such anarrangement is advantageous in terms of compactness. In a furtherdevelopment of the invention, two or more bearing constructions arearranged radially around the main shaft axis of the turbine and thearrangement further comprises a central shaft section. The central shaftsection is connectable to the turbine main shaft and interconnects thehub-side bearing seat of the static frame of each bearing construction.Preferably, the cone bases of each static frame are connected to eachother and are connected to the central shaft portion at a front side andat a rear side of the central shaft portion. The interconnection of thestatic frames at the heart of the hub improves the strength andload-transfer capabilities of the construction as a whole.

These and other advantages will become apparent from the detaileddescription and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described further, with reference to thefollowing Figures, in which:

FIG. 1 a, FIG. 1 b respectively show a perspective view and across-sectional view of a first example of a bearing constructionaccording to the invention;

FIG. 2 shows a perspective view of a second example of a bearingconstruction according to the invention, mounted to a turbine hub;

FIG. 3 shows a cross-sectional view of an arrangement of three bearingconstructions according to the invention;

FIG. 4 shows a cross-section view of a further arrangement of threebearing constructions according to the invention; and

FIG. 5 shows an example of a wind turbine.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIG. 5 is a front view of a wind turbine 5 comprising three blades 10connected to a hub 20. The hub is connected via a main shaft (not shown)to a generator, arranged in a nacelle 30 mounted on a tower 40. Tomaximize the amount of energy captured by the blades while minimizingthe load on the blades, the wind turbine is equipped with an individualpitch control system. Each blade 10 is rotatable relative to the hub 20about a blade pitch axis, and is rotationally supported by a bearingconstruction.

In order to minimize friction, a bearing construction according to theinvention comprises axially spaced first and second bearings, which havea diameter that is significantly smaller than a blade root diameter ofthe turbine blade. The bearing construction further comprises mutuallyoverlapping frames which connect the first and second bearings to eachother. The frames must therefore be sufficiently robust to transmit thehigh application loads on the blade to the hub.

A first embodiment of a bearing construction according to the inventionis shown in a perspective view and in a cross-sectional view in FIG. 1 aand FIG. 1 b. The bearing construction 100 comprises a dynamic frame 110and a static frame 130, which are rotationally supported relative toeach other by means of first and second bearings 150, 160.

In use of the bearing construction, a wind turbine blade is mounted tothe dynamic frame 110 and the static frame 130 is mounted to the windturbine hub, which is in connection with the turbine main shaft. Thedynamic frame 110 comprises a cylindrical section to which the turbineblade is mounted and further comprises a conical section. The conicalsection has a large-diameter cone base 113 and a small-diameter coneapex 115 which are connected via frame bars 117. The conical section ofthe dynamic frame 110 extends along the blade pitch axis, inside of thecylindrical section.

The static frame also comprises a conical section with a large-diametercone base 133 and a small-diameter cone apex 135 joined by frame bars137. The conical sections of both frames are oriented in the samedirection, such that the cone apex 115 of the dynamic frame lies at thecone apex 135 of the static frame.

To enable a pitch angle of the turbine blade to be adjusted about theblade pitch axis, the dynamic frame 110 is rotationally supportedrelative to the static frame by means of a hub-side bearing 150 and ablade-side bearing 160, axially spaced from the hub-side bearing.

Thus, the dynamic frame 110 has a hub-side bearing seat 120 and ablade-side bearing seat 125 for the hub- and blade-side bearings 150,160 respectively, and the static frame 130 has a hub-side bearing seat140 and a blade-side bearing seat 145 for the hub- and blade-sidebearings 150, 160 respectively.

The blade-side bearing seat 125 of the dynamic frame is provided at thecone apex 115 and forms a housing part to which an outer ring of theblade-side bearing 160 is mounted. The blade-side bearing seat 145 ofthe static frame is provided at the static frame cone apex 135 and isformed by a shaft part that serves as an inner ring of the blade-sidebearing 160.

In the depicted example, the hub-side bearing seat 120 of the dynamicframe is located at a centre region of the of the cone base 113, andforms a housing part to which an outer ring of the hub-side bearing 150is mounted. The outer ring can be mounted directly to the bearing seat120 or, as shown in the example of FIG. 1 b, can be indirectly mountedto the bearing seat via a conical sleeve. The hub-side bearing seat 120lies in the plane of the cone base 113 of the dynamic frame and isjoined to the cone base 113 by three evenly spaced dynamic frame legs122, which extend in a radial direction. The hub-side bearing seat 140of the static frame is likewise located at a central region of thestatic frame cone base 133, and forms a shaft part to which an innerring of the hub-side bearing 150 is mounted. The shaft part 140 isjoined to the cone base 133 of the static frame by three evenly spacedstatic frame legs 142 which penetrate through openings between the legs122 of the dynamic frame. The cone base 133 of the static frame liesaxially closer to a hub-side 180 of the bearing construction than thecone base 113 of the dynamic frame, and the static frame legs 142 extendin an axial direction through the openings between the dynamic framelegs, then extend radially inwards to the hub-side bearing seat 140(shaft part) of the static frame.

The maximum relative angular displacement between the static and dynamicframes is dependent on the thickness of the frame legs 122, 142 and onthe circumference of a penetration region where the legs pass througheach other. In the depicted example, the region of penetration isarranged at the cone base 113 of the dynamic frame and close to the conebase 133 of the static frame. In other words, the penetration region isarranged at a large-diameter part of both frames, meaning that the framelegs can be made sufficiently thick to withstand high loads, whileretaining an acceptable range of relative angular rotation of around 100degrees.

An example of a second embodiment of a bearing construction according tothe invention is depicted in FIG. 2. The bearing construction 200 ismounted to the hub 205 of a wind turbine. and comprises a dynamic framewith a first conical section 211 and a second conical section 212 thatis oppositely oriented from the first conical section. A common conebase 213 connects the first and second conical sections 211, 222. Thedynamic frame is thus essentially diamond shaped.

The first conical section has a cone apex, where a bearing seat for ahub-side bearing (not visible) is provided. The dynamic frame furthercomprises three evenly spaced frame legs 222 with openings in between.The dynamic frame legs 222 form part of the first conical section 211and connect the cone apex of the first conical section to the cone base213. The second conical section 212 has a cone apex 215 with a bearingseat for a blade-side bearing (not visible). In the depicted example,the second conical section is formed by a solid cone. A frame or trussconfiguration is also possible.

The static frame is also essentially diamond shaped and comprisesoppositely oriented first and second conical sections which areconnected via a cone base 233. At a cone apex (not visible) of the firstconical section 231, a bearing seat for the hub-side bearing (notvisible) is provided. The static frame further comprises a cylindricalhub interface 234 that is mounted to the hub 205. The hub interface 234comprises three static frame legs 242, which are evenly spaced aroundthe circumference and which are connected to the cone base 233 of thestatic frame. The static frame legs 242 have openings in between, thoughwhich the dynamic frame legs 222 penetrate. In accordance with theinvention, the penetration region is provided close to the cone bases213, 233 of the static and dynamic frames, which again optimizes therange of relative angular displacement for the leg thickness that isrequired in order to transmit the high loads.

The second conical section of the static frame (not visible) extendsinside the second conical section 212 of the dynamic frame, and has acone apex where a bearing seat is provided for the blade-side bearing.The second conical section may be a solid cone or may be formed from aframe or truss configuration.

An advantage of a diamond configuration of the static and dynamic framesis that the force lines through the frames are relatively short, meaningthat less material is needed. A robust construction of lower weight canthus be achieved.

In the second embodiment of the invention (diamond configuration) thehub-side bearing is arranged at the cone apex of two conical sections.The first embodiment of the invention, where the static and dynamicframes each comprise only one conical section, can also be executed suchthat the hub-side bearing is located at the cone apices. An advantage ofdoing this is that the hub-side bearing can be arranged closer to arotation axis of the turbine main shaft. This can be seen in FIG. 3,which shows an arrangement of three bearing constructions according to afurther example of the second embodiment of the invention. NB: Forclarity reasons, not all of the features common to each have beenprovided with reference numerals

The dynamic frame of each bearing construction has a first conicalsection 311 and an oppositely oriented second conical section 312, whichare connected by a cone base 313. The dynamic frame further comprises acentral shaft section 318 with axially spaced bearing seats 320, 325 fora hub-side bearing 350 and a blade-side bearing 360. The first andsecond conical sections 311, 312 are connected to the bearing seats onthe shaft section 318 at an apex region of each conical section.

The static frame of each bearing construction has a first conicalsection 331 and an oppositely oriented second conical section 332, whichare connected by a cone base 333. The cone base 333 is mounted to thehub 305 and lies radially outside of the cone base 313 of the dynamicframe. Thus, the first conical section 311, 331 of each frame extendstowards a centre region of the hub 305, where the turbine main shaft(not shown) is located. An assembly of bearing constructions accordingto the depicted embodiment is thus compact.

Further, the static frame of each bearing construction has a firstbearing seat 340 for the hub-side bearing 350 and a second bearing seat345 for the blade-side bearing 360. As before, the first and secondbearing seats of each frame are arranged at a cone apex of therespective conical section.

In this example, the first and second conical sections 311, 312 of thedynamic frame are arranged inside the first and second conical sections331, 332 of the static frame respectively. The dynamic frame furthercomprises a blade-mounting interface 314 and has three dynamic framelegs 322 that connect blade-mounting interface 314 to the cone base 313of the dynamic frame. The static frame has three static frame legs 342that connect the cone base 333 of the static frame to the second bearingseat 345. The static frame legs 342 form part of the second conicalsection of the static frame. As before, the static frame legs penetratethrough the openings between the dynamic frame legs 322 in alarge-diameter region of each frame, at the respective cone base 313,333.

As mentioned, the hub and bearing construction becomes more compact whenthe hub-side bearing 350 is arranged in a central region of the hub. Toprovide the construction as whole with additional robustness, it isadvantageous if the first bearing seats 340 of each static frame areinterconnected. The first bearing seats may be formed by shaft sectionsthat extend in a radial direction from a central shaft, whereby thecentral shaft is connected to the turbine main shaft. In the example ofFIG. 3, the first bearing seats 340 are formed by a bore for receivingthe outer ring of the hub-side bearing 340. The shaft sections wouldthen be hollow shaft sections.

In an alternative example, as depicted in the assembly FIG. 4, the firstbearing seat of the static frames is a shaft section to which the innerring of the hub-side bearing is mounted.

The assembly comprises three bearing constructions according to theinvention, whereby the static frames of the constructions areinterconnected to form an integrated hub and bearing assembly.

Each bearing construction has a dynamic frame comprising a first conicalsection 411 and an oppositely oriented second conical section 412 thatextends from a cylindrical cone base 413. A bearing seat 420, 425 forthe hub-side bearing and the blade-side bearing are provided at the apex415 of each conical section. Further, each dynamic frame has threedynamic frame legs 422 with openings in between, arranged at evenintervals around a cylindrical cone base 413. In this example, thedynamic frame legs extend in an essentially axial direction and formpart of the cone base 413 that interconnects the first and secondconical sections.

The static frame of each bearing construction comprises a conicalsection 431, whereby a bearing seat 445 for the blade-side bearing isprovided at an apex 435 of the conical section. A cone base 433 of eachstatic conical section 431 is connected to the cone base of an adjacentsection. Further, each static frame has three evenly spaced static framelegs 442 which extend from the cone base 433 to the cone apex 435 andpass through the openings between the dynamic frame legs 422. Again, thelegs penetrate through each other in a large-diameter region of eachframe, meaning that the legs can be sufficiently thick and strong forsupporting the high loads from the turbine blade, while enabling asufficient degree of relative rotation.

The assembly further comprises a central shaft 470, which extends alongan axis of the turbine main shaft. Extending in a radial direction, thecentral shaft 470 has three shaft sections which form the hub-sidebearing seat 440 of the static frame of each bearing construction.Suitably, the cone base 433 of each static frame is also structurallyconnected to the central shaft 470 at a front side of the hub 405 and ata rear side of the hub. This interconnection of the static frames at theheart of the hub and bearing assembly couples the static frames firmlytogether, which significantly increases the strength and stiffness ofthe overall assembly. Furthermore, the loads on the hub-side bearing aretransmitted to the hub at the central shaft 470, enabling a more directtransfer of those loads to the turbine main shaft in comparison withconventional wind turbine hubs.

A number of aspects/embodiments of the invention have been described. Itis to be understood that each aspect/embodiment may be combined with anyother aspect/embodiment. Moreover the invention is not restricted to thedescribed embodiments, but may be varied within the scope of theaccompanying patent claims.

REFERENCE NUMERALS

-   5 Wind turbine-   10 Turbine blade-   20 Turbine hub-   30 Nacelle-   40 Tower-   100 Bearing construction-   110 Dynamic frame-   113 Cone base of conical section of dynamic frame-   115 Cone apex of conical section of dynamic frame-   117 Frame bars of conical section of dynamic frame-   120 First bearing seat of dynamic frame-   122 Dynamic frame leg-   125 Second bearing seat of dynamic frame-   130 Static frame-   133 Cone base of conical section of static frame-   135 Cone apex of conical section of static frame-   137 Frame bars of conical section of static frame-   140 First bearing seat of static frame-   142 Static frame leg-   145 Second bearing seat of static frame-   150 First bearing-   160 Second bearing-   180 Hub-side of bearing construction-   200 Bearing construction-   205 Hub of wind turbine-   211 First conical section of dynamic frame-   212 Second conical section of dynamic frame-   213 Cone base of conical sections of dynamic frame-   215 Cone apex of conical sections of dynamic frame-   222 Dynamic frame leg-   231 First conical section of static frame-   233 Cone base of conical section of dynamic frame-   234 cylindrical hub interface of static frame-   242 Static frame leg-   305 Hub of wind turbine-   311 First conical section of dynamic frame-   312 Second conical section of dynamic frame-   313 Cone base of conical sections of dynamic frame-   314 Cylindrical blade interface of dynamic frame-   315 Cone apex of conical sections of dynamic frame-   318 Shaft section of dynamic frame-   320 Hub-side bearing seat of dynamic frame-   322 Dynamic frame leg-   325 Blade-side bearing seat of dynamic frame-   331 First conical section of static frame-   332 Second conical section of static frame-   333 Cone base of conical section of dynamic frame-   340 Hub-side bearing seat of static frame-   342 Static frame leg-   345 Blade-side bearing seat of static frame-   350 Hub-side bearing-   360 Blade-side bearing-   411 First conical section of dynamic frame-   412 Second conical section of dynamic frame-   413 Cone base of conical sections of dynamic frame-   415 Cone apex of conical sections of dynamic frame-   420 Hub-side bearing seat of dynamic frame-   422 Dynamic frame leg-   425 Blade-side bearing seat of dynamic frame-   431 First conical section of static frame-   433 Cone base of conical section of dynamic frame-   440 Hub-side bearing seat of static frame-   442 Static frame leg-   445 Blade-side bearing seat of static frame-   470 Central shaft portion on which first bearing seat of each static    frame is provided

1. A bearing construction for rotationally supporting a turbine bladerelative to a turbine hub, comprising: a dynamic frame configured forconnection to the turbine blade; a static frame configured forconnection to the turbine hub; and a first axially spaced bearing and asecond axially spaced bearing adapted to rotationally support thedynamic frame relative to the static frame, wherein each of the dynamicand static frame comprises: a first bearing seat for the first axiallyspaced bearing and a second bearing seat for the second axially spacedbearing; a first conical section having a cone base and a cone apex; andat least two frame legs with openings in between; wherein the dynamicand static frames are mutually overlapping, such that the frame legs ofone frame pass through the openings between the frame legs of the otherframe, wherein the first conical section of the static frame and thefirst conical section of the dynamic frame are oriented in the samedirection, wherein the cone apex of each first conical section isprovided with a bearing seat.
 2. The bearing construction according toclaim 1, wherein the frame legs pass through each other at alarge-diameter region of the static frame and of the dynamic frame,close to or at the cone base of each conical section.
 3. The bearingconstruction according to claim 1, wherein the cone apex of each firstconical section is arranged at a hub side of the construction andcomprises a hub-side bearing seat.
 4. The bearing construction accordingto claim 3, wherein the hub-side bearing seat of the static frame isarranged in a central region of the hub, close to a rotation axis of theturbine main shaft.
 5. The bearing construction according to claim 4,wherein the hub-side bearing seat is connected to the hub-side bearingseat of a further static frame, the connection comprising a centralshaft portion that is configured for mounting to the turbine main shaft.6. The bearing construction according to claim 1, wherein each of thestatic frame and the dynamic frame comprises only a first conicalsection, and a bearing seat arrangement being one of: wherein a bearingseat of the dynamic frame is arranged in a plane of the cone base of thedynamic frame, or wherein a bearing seat of the static frame is arrangedin a plane of the cone base of the static frame.
 7. The bearingconstruction according to claim 6, wherein the frame legs of the framewhich has its bearing seat in the plane of the cone base, extend in apurely radial direction.
 8. The bearing construction according to claim1, wherein at least one of the static and dynamic frames furthercomprises: a second conical section oppositely oriented from the firstconical section, whereby a cone apex of the second conical section isprovided with a bearing seat.
 9. The bearing construction according toclaim 8, wherein the frame legs of the at least one frame form part of aconical section of that frame.
 10. The bearing construction according toclaim 8, wherein the dynamic frame further comprises a cylindrical bladeinterface that extends from the cone base of the first conical section,and wherein the dynamic frame legs form part of the cylindrical bladeinterface.
 11. The bearing construction according to claim 1, whereinthe cone base of the first conical section of the static frame isconfigured for mounting to the hub.
 12. The bearing constructionaccording to claim 8, wherein the static frame further comprises acylindrical hub interface, configured for mounting to the hub, andwherein the static frame legs form part of the cylindrical hub interfaceand extend from the cone base of the static frame.
 13. The bearingconstruction according to claim 1, wherein one or both of the firstbearing and the second bearing comprises a radial spherical plainbearing.
 14. The bearing construction according to claim 1, wherein thefirst bearing seat and the second bearing seat of the static frame areconfigured for receiving one of a bearing inner ring or a bearing outerring.
 15. The bearing construction according to claim 1, wherein thefirst bearing seat and the second bearing seat of the dynamic frame areconfigured for receiving one of a bearing inner ring or a bearing outerring.
 16. The bearing construction according to claim 1, wherein thefirst bearing seat of one of the dynamic frame or the static frame isconfigured to receive a bearing inner ring and the second bearing seatof the one of the dynamic frame or the static frame is configured toreceive a bearing outer ring.